Conventionally used system of dehumidifying and drying powdered or granular material includes a drying hopper for storing a powdered or granular material, a dehumidifying unit having an absorbing body and a plurality of gas routes provided for them.
According to such a dehumidifying and drying system of powdered or granular material, for example, a processing gas which has been used for drying and dehumidifying a powdered or granular material in the drying hopper and is exhausted from the drying hopper is passed through a dehumidifying rotor (honeycomb rotor) which is filled with an absorbing agent (drying agent, moisture absorbing agent) and has a plurality of gas flow paths formed like a honeycomb. The moisture contained in the processing gas is absorbed at the dehumidifying rotor, thereby dehumidifying the processing gas, and the dehumidified processing gas is introduced in the drying hopper again to dehumidify and dry a powdered or granular material.
For example, the following patent document 1 suggests a dehumidifying and drying apparatus (drying apparatus of granulate material) in which a drying hopper (hopper for granulate material) of powdered or granular material (granulate material) and a honeycomb rotor (absorption dryer) including an absorbing agent (absorbing material) are interconnected with a plurality of air pipes (duct).
Such a conventional dehumidifying and drying apparatus is explained referring to FIG. 9.
The term used in the patent document 1 is described in parentheses for descriptive purposes.
FIG. 9 is a diagrammatic explanatory view schematically showing the conventional dehumidifying and drying apparatus.
The conventional dehumidifying and drying apparatus 1 in the figure roughly has a drying hopper 2 for storing a powdered or granular material, a honeycomb rotor 3 for dehumidifying a processing gas (air) exhausted from the drying hopper 2, and a plurality of air pipes 10-14 interconnecting them.
The honeycomb rotor 3 includes an absorbing agent such as silica gel and is designed to rotate in a clockwise direction (in a direction shown with an outlined arrow) and to continuously execute absorption of the moisture contained in the processing gas passing through the rotor 3 and regeneration of the absorbing body containing moisture.
Namely, the processing gas is dehumidified in a drying zone 3a in the honeycomb rotor 3, the absorbing agent in the honeycomb rotor 3 is recycled in a regenerating zone 3b, and the absorbing agent is cooled down in a cooling zone 3c. 
The processing gas passed through the drying zone 3a becomes a dehumidified air being dehumidified by the absorbing agent (moisture is absorbed), passes through the air pipe 10, is heated by a heater 4 provided for the drying hopper 2, is introduced in the drying hopper 2, and is used for dehumidifying and drying a powdered or granular material.
The processing gas which has been used for dehumidifying and drying a powdered or granular material in the drying hopper 2 and contains moisture passes through the air pipe 11 connected above the drying hopper 2, the air pipe 13 connected to the air pipe 11, a filter 5, a cooler 6, and a blower 7, in this order, and is introduced into the honeycomb rotor 3 again via the air pipe 14.
Thus, the reason why the cooler 6 is provided upstream of the honeycomb rotor 3 is to protect the blower 7 positioned at its downstream and to increase the absorption amount of moisture by reducing the temperature of the heated and regenerated absorbing agent.
The air pipe 14 is diverged into an air pipe 14b for introducing a cooling gas in the cooling zone 3c, mentioned later, and an air pipe 14a for introducing a cooling gas into the drying zone 3a. 
The absorbing agent having moisture in the drying zone 3a reaches the regenerating zone 3b. 
In the regenerating zone 3b, heated air which is sucked by a regenerating blower 8 and is heated by a regenerating heater 9, passes through the regenerating zone 3b via an air pipe 15 as a hot air, and the temperature of absorbing agent is increased to eliminate moisture, thereby regenerating the absorbing agent with moisture.
The absorbing agent thus regenerated with a hot air in the regenerating zone 3b reaches the cooling zone 3c and is cooled down by a cooling gas introduced via the air pipe 14b in order to enhance the absorption ability of the absorbing agent. Thus used cooling gas flows via the air pipe 12 together with the processing gas which has been used for dehumidifying and drying a powdered or granular material in the drying hopper 2 and is exhausted therefrom, passes through the air pipe 13, the filter 5, the cooler 6, and the blower 7, in this order, and is introduced into the honeycomb rotor 3 again via the air pipe 14.
A collector (conveyor unit) 2a is provided above the drying hopper 2 and has a temperature sensor of powdered or granular material (temperature sensor of granulate material) 2b for measuring the temperature of the powdered or granular material temporarily stored in the collector 2a. Namely, the temperature of the powdered or granular material just before being charged in the drying hopper 2 is measured by the temperature sensor for powdered or granular material 2b. 
Further, the air pipe 11 has a temperature sensor 11a for measuring the temperature of the processing gas exhausted from the drying hopper 2.
Based on the difference between the value measured by the temperature sensor 11a and the value measured by the temperature sensor of powdered or granular material 2b, the rotary speed of the blower 7 is changed by a control system 16 connected with each temperature sensor 2b, 11a, thereby adjusting the flow amount of the processing gas to be fed in the drying hopper 2.
The flow amount of the processing gas to be fed in the drying hopper 2 is adjusted such that the temperature difference between the value measured by the temperature sensor 11a and the value measured by the temperature sensor of powdered or granular material 2b becomes around 2 or 3 degrees centigrade.
According to such a structure of the dehumidifying and drying apparatus 1 described in the patent document 1, the processing gas can be continuously dehumidified by the honeycomb rotor 3 and the dehumidified gas can be continuously introduced into the drying hopper 2.
Further, the patent document 1 explains that energy can be saved when the flow amount of the processing gas to be fed in the drying hopper 2 is adjusted such that the temperature difference between the measured value by the temperature sensor 11a and the measured value by the temperature sensor of powdered or granular material 2b becomes around 2 or 3 degrees centigrade.
Namely, the flow amount of the processing gas to be fed in the drying hopper 2 is adjusted such that the temperature of the processing gas exhausted from the drying hopper 2 becomes 2 or 3 degrees centigrade higher than the temperature of the powder or granular material just before being charged to the upper part of the drying hopper 2. Accordingly, it is explained that successive energy wastage accompanied with cooling of the processing gas exhausted from the drying hopper 2 and with re-heating of the processing gas before feeding to the drying hopper 2 can be reduced.    Patent Document 1 Japanese Patent Application (not examined) JP-2005-140497-A